JP4931959B2 - Light source device, light irradiation device including the light source device, image reading device including the light irradiation device, and image forming device including the image reading device - Google Patents

Description

  The present invention relates to a light source device formed by arranging a plurality of light emitting elements, a light irradiation device including the light source device, an image reading device including the light irradiation device, and an image including the image reading device. The present invention relates to a forming apparatus.

  An image forming apparatus such as a copying machine or a facsimile includes an image reading apparatus for reading an image of a document. This image reading apparatus is generally composed of a document placing plate, a document pressing plate, an illumination unit (light irradiation device), and a photoelectric conversion unit.

  Among these, the document placing plate is formed of a translucent material and has a function of placing the document on the surface. The document pressing plate has a function of pressing the back surface of the document placed on the surface of the document placing plate.

  The illumination unit moves along the document placement plate in the scanning direction, which is a direction intersecting the document width direction, and transmits the irradiation light through the document placement plate so that the document is in the width direction of the document. It has a function to irradiate. The photoelectric conversion unit has a function of converting the reflected light (target object reflected light) irradiated by the illumination unit and reflected from the document into an image signal.

  Recently, a light source device using a light emitting diode as a light source has been adopted for the illumination unit in the image reading apparatus from the viewpoint of life and power consumption. As a light source device using this light emitting diode, a light source device having a configuration in which the light emitting diodes are arranged on a substrate at an interval has been proposed (for example, see FIG. 1 of Patent Document 1).

  The light source device described in Patent Document 1 is a light source device used for a liquid crystal display. In such a light source device having a configuration in which light emitting diodes are arranged on a substrate at intervals, the light source device is directly connected to the light source diode. Irradiation light is composed of the direct light radiated and the substrate reflected light in which the light radiated from the light emitting diode is reflected by the substrate. Further, the light source device having such a configuration has a simple configuration and can be said to be advantageous in terms of cost.

JP 2003-257230 A

  By the way, in the illumination unit (light irradiation device) of the image reading apparatus described above, in a light source device using light emitting diodes as light sources, the light emitting diodes are usually arranged in a line at regular intervals. For this reason, light and dark unevenness tends to occur in the light applied to the document.

  However, in the illumination unit of the image reading apparatus described above, in order to increase the accuracy of reading the image of the document, it is effective to reduce the unevenness of light and darkness of the light applied to the document as much as possible. As described above, in the light source device as described in Patent Document 1 in which the light emitting diodes are arranged on the substrate at an interval, the irradiation light is emitted directly from the light emitting diode and from the light emitting diode. The emitted light is composed of substrate reflected light reflected by the substrate.

In view of this, for example, in the light source device described in Patent Document 1, a device is devised to suppress the substrate reflected light in which the light emitted from the light emitting diode is reflected by the substrate. That is, the surface of the substrate fitted with light-emitting diodes, in the area of the extension building black (optical axis direction of the irradiation light) forward wider than the width of the light emitting surface is formed from the lower end of the light emitting surface of the light emitting diode Yes.

  In the light source device described in Patent Document 1, the black area is formed wider than the width of the light emitting surface of the light emitting diode. Therefore, as an effect, the substrate reflected light reflected by the substrate is suppressed, but the effect of suppressing light unevenness of light only by reducing the amount of light emitted by suppressing this substrate reflected light, It is thought that there are few.

  Therefore, the present invention has been made to cope with the above situation, and uses a light emitting diode as a light source, has a simple configuration, and has an effect of suppressing light unevenness of light, An object of the present invention is to provide a light irradiation device including the light source device, an image reading device including the light irradiation device, and an image forming apparatus including the image reading device.

A light source device of the present invention, a plurality of light emitting elements having a light emitting surface, disposed in a row at intervals on the surface of the substrate, emits irradiation Shako along the light emitting surface of the light emitting element on a surface of the substrate It is a light source device.

In this light source device , a light reflection suppression area is formed on the surface of the substrate, and the light reflection suppression area is provided from the light emitting surface to the end of the substrate along a direction orthogonal to the light emitting surface, The light reflection is higher on the surface of the substrate than the portion where the light reflection suppression area is formed between the light emitting surface and the edge of the substrate. It is characterized by a promotion area .

In the above light source device, the light emitting elements are arranged in a line on the substrate at an interval, and the irradiation light includes direct light emitted directly from the light emitting element and light emitted from the light emitting element on the substrate. It is comprised with the reflected substrate reflected light.

The light reflection suppression area is formed with a width narrower than the width of the light emitting surface of the light emitting element. Therefore, reflection of light emitted from the central portion of the light emitting surface of the light emitting element is suppressed in the light reflection suppressing area, and direct light emitted from the light emitting element is mainly used as irradiation light. In contrast, with respect to the light emitted from both end peripheral portion of the light-emitting surface of the light-emitting element, the light reflection suppression area is narrower than the width of the light emitting surface of the light emitting element, is reflected by the light reflection promoting area A For this reason, it is possible to enhance the irradiation light composed of the direct light and the substrate reflected light by the radiated light from the peripheral portions at both ends of the light emitting surface. For this reason, the brightness of the irradiated light from the peripheral portions of both ends of the light emitting surface can be brought close to the brightness of the direct light mainly emitted from the central portion of the light emitting surface of the light emitting element. Can be suppressed.

  Therefore, light unevenness of light is suppressed as the whole irradiation light of the light source device. Further, the light source device described above is configured by arranging light emitting elements on a substrate at intervals, and has a simple structure.

  Therefore, according to the light source device described above, the structure of the light source device can be simplified, and uneven light and darkness of the light from the light source device can be suppressed.

  In the above light source device, a side-type light emitting element having a light emitting surface on a side surface is generally used as the light emitting element. Since this side-type light emitting element is provided with a light-emitting surface that emits light on the side surface, in the state where the side-type light-emitting element is attached to the surface of the substrate, the light-emitting surface is generally the same as the surface of the substrate. It is almost vertical.

  Moreover, in said light source device, it is suitable for a light reflection suppression area to be planar, and to set the color of this surface to black or gray. This is because these black colors or gray colors can reduce the light reflectance as compared with other colors, and are optimal as a light reflection suppression area.

  In the light source device including the light reflection promotion area, it is preferable that the light reflection promotion area is a white surface. This is because this white color can increase the reflectance of light as compared with other colors, and is therefore optimal as a light reflection promoting area. The light reflection promotion area is generally formed by silk printing.

  Furthermore, in the light source device including the above-described light reflection promotion area, it is preferable that the white light reflection promotion area is formed on the surface of the white resist layer formed on the surface of the substrate.

  A substrate on which the light emitting element is mounted usually has a copper foil pattern as a circuit formed on the surface of a plate-like base material, and a resist layer formed thereon (surface). In this case, the color of the resist layer is white. The white light reflection promoting area is formed on (on the surface of) the white resist layer.

  Therefore, by making the resist layer white, the light reflectance of the white light reflection promoting area formed thereon can be further increased.

The light irradiation device of the present invention can be configured using any of the light source devices described above. This light irradiation apparatus is an apparatus that obtains reflected light from a light irradiation object by irradiating the light irradiation object with the light source device.

In this light irradiation device, the optical axis of the irradiation light that irradiates the light irradiation target with the light emitted from the light emitting surface of the side-type light emitting element in the light source device is the same as the surface to be irradiated of the light irradiation target. It is configured by being arranged at a position inclined with respect to the optical axis of the reflected light from the light irradiation object in the orthogonal direction .

  The light irradiation device configured as described above has the functions and effects provided in the light source device described above.

  Said light irradiation apparatus can be comprised using one light source device mentioned above. Or it can also comprise by using two said light source devices.

When a light irradiation device is configured by using two light source devices as described above, the optical axis of the irradiation light of one light source device is reflected from the light irradiation target in a direction orthogonal to the irradiated surface of the light irradiation target. Two light source devices are arranged at positions symmetrical to the optical axis of the irradiation light of the other light source device with the optical axis of light as the symmetry axis.

In this way, the light irradiation device having two light source device is configured, as compared with the light irradiation apparatus comprising a single light source device, to enhance the illumination light.

In addition, the image reading apparatus of the present invention can be configured using the light irradiation apparatus described above. Specifically, the image reading apparatus of the present invention irradiates a light irradiation object with light, outputs the reflected light from the light irradiation object, and the light output from the light irradiation apparatus. An image sensor that converts the image signal. The image reading apparatus using the above-described light irradiation apparatus has functions and effects provided in the above-described light irradiation apparatus.

In addition, the image forming apparatus of the present invention can be configured using the above-described image reading apparatus as one of the constituent elements. Specifically, an image forming apparatus according to the present invention includes the above-described image reading device, and forms an image based on an image read by the image reading device. The image forming apparatus using the above-described image reading apparatus has functions and effects provided in the above-described image reading apparatus.

According to the present invention, the light reflection suppression area of the light source device is formed with a width narrower than the width of the light emitting surface of the light emitting element. Therefore, reflection of light emitted from the central portion of the light emitting surface of the light emitting element is suppressed in the light reflection suppressing area, and direct light emitted from the light emitting element is mainly used as irradiation light. In contrast, light emitted from both end peripheral portion of the light-emitting surface of the light-emitting element, the light reflection suppression area is narrower than the width of the light emitting surface of the light emitting element, from being reflected by the light reflection promoting area, reflecting Is promoted. Therefore, it is possible to enhance the irradiation light composed of the direct light and the substrate reflected light by the radiated light from the peripheral portions at both ends of the light emitting surface. For this reason, the brightness of the irradiated light from the peripheral portions of both ends of the light emitting surface can be brought close to the brightness of the direct light mainly emitted from the central portion of the light emitting surface of the light emitting element. Light unevenness of light can be suppressed.

  Therefore, light unevenness of light is suppressed as the entire irradiation light. Further, the light source device described above is configured by arranging light emitting elements on a substrate at intervals, and has a simple structure. Therefore, the structure of the light source device can be simplified, and unevenness in light and darkness of the light source device can be suppressed.

  Further, the light reflection suppression area of the light source device is planar, and the color of this surface is black or gray. Therefore, the light reflectance of the light reflection suppression area of the light source device can be lowered as compared with other colors.

  Further, the light reflection promotion area of the light source device is planar, and the color of this surface is white. Therefore, the light reflectance of the light reflection promoting area of the light source device can be increased as compared with other colors.

  Further, a white light reflection promoting area is formed on the surface of the white resist layer formed on the surface of the substrate. Therefore, when the resist layer is white, the light reflectance of the white light reflection promoting area formed thereon can be further increased.

It is a top view of the light source board | substrate in embodiment. It is a front view of the light source board | substrate in embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. It is the elements on larger scale of FIG. It is the perspective view which showed the external appearance of the illumination unit in embodiment. FIG. 6 is a cross-sectional view taken along the line BB in FIG. 5. It is the elements on larger scale of FIG. It is the elements on larger scale of the illumination unit of the other example in embodiment. 1 is a cross-sectional view of an image reading apparatus in an embodiment. It is a top view of the light source board (the 1) for the comparison of the effect of the image reading device in an embodiment. It is a top view of the light source board (the 2) for comparison of the effect of the image reading device in an embodiment. 6 is a graph (part 1) showing an experimental result of an effect of the image reading apparatus in the embodiment. 6 is a graph (part 2) showing an experimental result of the effect of the image reading apparatus in the embodiment. FIG. 10 is a graph (part 3) illustrating an experimental result of the effect of the image reading device in the embodiment. It is the illumination intensity analysis figure by the theoretical analysis of the image reading apparatus in embodiment (the 1). It is the illumination intensity analysis figure by the theoretical analysis of the image reading apparatus in embodiment (the 2). It is the illumination intensity analysis figure by the theoretical analysis of the image reading apparatus in embodiment (the 3). 3 is a graph showing illuminance by theoretical analysis of the image reading apparatus in the embodiment. It is the table which showed the experimental result of the effect of the image reading device in the form of execution.

  Next, a light source substrate (light source device), an illumination unit (light irradiation device) including the light source substrate, an image reading device including the illumination unit, and the image reading device according to an embodiment of the present invention are provided. The image forming apparatus will be described in detail with reference to the drawings.

  First, the light source substrate in the present embodiment will be described. The light source substrate in the present embodiment corresponds to the light source device described above. 1 is a plan view of a light source substrate 10 in the present embodiment, FIG. 2 is a front view thereof, FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is a partially enlarged view of FIG. is there. 1 to 4, the light source substrate 10 includes a light emitting diode 11 and a substrate 12.

  Among these, as shown in FIGS. 2 and 3, the substrate 12 has a plate-like base material 12a formed of paper phenol or the like, and a copper foil pattern 12b formed as a circuit on the surface of the base material 12a. It is comprised with the resist layer 12c formed on this copper foil pattern 12b (surface). The resist layer 12c is white. Further, a white layer 12d is formed on the white resist layer 12c by silk printing.

As shown in FIGS. 1 to 3, a side type light emitting diode 11 which is a side type light emitting element having a light emitting surface 11a on a side surface is provided on the surface of the substrate 12 formed as described above. from as irradiation Shako along the surface of the substrate 12 is radiated toward the light emitting surface 11a in the same direction, at intervals on the surface of the substrate 12, it is mounted in a row.

  The light-emitting diode 11 that is the side-type light-emitting element has a rectangular parallelepiped shape, and the light-emitting surface 11 a that emits light of the light-emitting diode 11 is formed on the side surface with respect to the apex surface of the light-emitting diode 11. In a state where the side type light emitting diode 11 is attached to the surface of the substrate 12, the light emitting surface 11 a is substantially perpendicular to the surface of the substrate 12.

  As shown in FIG. 4, the width of the light emitting surface 11a of the light emitting diode 11 is 2 mm, and the width of the wall surface of the light emitting diode 11 provided with the light emitting surface 11a is 2.5 mm.

Further, in the light source substrate 10, as shown in FIG. 4, the black layer 13 is formed on the white layer 12 d (surface) that is the surface of the substrate 12. This black layer 13 is on the white layer 12d (surface), which is the surface of the substrate 12, and in a direction perpendicular to the light emitting surface 11a from the lower end of the light emitting surface 11a of the light emitting diode 11 (optical axis direction of irradiated light). to the end of the substrate 12 in the extension building so along, a narrow width 1mm than the width of the light emitting surface 11a, and is formed by printing.

  The black layer 13 corresponds to the light reflection suppression area described above. In the light source substrate 10 described above, the black layer 13 corresponding to the light reflection suppression area is black, but may be gray. Since these black or gray can make the light reflectance lower than other colors, it is excellent as the color of the light reflection suppression area.

In the light source substrate 10 described above, the light emitting diodes 11 are arranged in a row on the substrate 12 at intervals, and the irradiation light emitted from the light source substrate 10 is emitted from the light emitting diodes 11 as shown in FIG. A direct light 21 that is directly emitted and a substrate reflected light 22 in which the light emitted from the light emitting diode 11 is reflected on the surface of the substrate 12 are configured.

  Further, the black layer 13 corresponding to the above-described light reflection suppression area is formed with a width of 1 mm which is narrower than the width of 2 mm of the light emitting surface 11 a of the light emitting diode 11. For this reason, the light emitted from the central portion of the light emitting surface 11 a of the light emitting diode 11 is suppressed from being reflected by the black layer 13, and the direct light 21 emitted from the light emitting diode 11 is mainly used as the irradiation light.

  On the other hand, the light emitted from the peripheral portions of both ends of the light emitting surface 11a of the light emitting diode 11 has a black layer 13 because the black layer 13 which is a light reflection suppression area is narrower than the width of the light emitting surface 11a of the light emitting diode 11. Since the light is reflected by a portion other than 13, the reflection is not suppressed, and the irradiation light is composed of the direct light 21 emitted from the light emitting diode 11 and the substrate reflected light 22. For this reason, light unevenness of light is suppressed as the entire irradiation light in the light source substrate 10.

  In the light source substrate 10, as described above, the black layer 13 is formed on (on the surface of) the white layer 12 d that is the surface of the substrate 12. That is, the white layer 12d is exposed at portions other than the black layer 13, and this portion is white.

Of the white portion where the white layer 12d is exposed, the black layer 13 corresponding to the above-described light reflection suppression area between the light emitting surface 11a of the light emitting diode 11 on the surface of the substrate 12 and the end portion of the substrate 12. The part other than corresponds to the above-described light reflection promotion area. This light reflection promotion area has the following functions.

  That is, since the light reflection promotion area is formed, the white layer 12d that is a portion other than the black layer 13 is exposed from the light emitted from the peripheral portions of both ends of the light emitting surface 11a of the light emitting diode 11. It is reflected by the white part and the reflection is promoted. Accordingly, it is possible to enhance the irradiation light composed of the direct light 21 and the substrate reflected light 22 by the radiated light from the peripheral portions of the light emitting surface 11a of the light emitting diode 11.

  Therefore, the brightness of the irradiation light by the radiated light from the peripheral portions of both ends of the light emitting surface 11a of the light emitting diode 11 is brought close to the brightness of the irradiation light mainly composed of the direct light 21 from the central portion of the light emitting surface 11a of the light emitting diode 11. And light and dark unevenness of light emitted from the light source substrate 10 can be suppressed.

  Regarding the above point, in the light source substrate 10, the white layer 12 d is white because white can increase the reflectance of light compared to other colors. Further, as described above, the white layer 12d is formed on the white resist layer 12c. This is because by making the resist layer 12c white, the reflectance of light can be increased as compared with the case where the resist layer 12c has a color other than white, as will be described later.

  Next, the illumination unit in the present embodiment will be described. The illumination unit in the present embodiment corresponds to the above-described light irradiation device. The illumination unit includes the light source substrate 10 described above, and is an apparatus that uses the light source substrate 10 to irradiate a light irradiation object with light to obtain object reflection light.

  5 is a perspective view showing the appearance of the illumination unit 4, FIG. 6 is a cross-sectional view taken along the line BB of FIG. 5, and FIG. 7 is a partially enlarged view of FIG. 6 and 7, the document placing plate 2 is a part of an image reading device 1 to be described later on which the illumination unit 4 is mounted, and the document 9 is light from which an image is read by the image reading device 1. It is an irradiation object.

5-7, the illumination unit 4 is comprised using two said light source substrates 10. In FIG. The illumination unit 4 has optical axes of irradiation lights 21 and 22 for irradiating light 9 emitted from the light-emitting surface 11a of the side-type light-emitting diode 11 used for the light source substrate 10 onto the document 9 that is a light irradiation object. The light source substrate 10 is arranged in the illumination unit 4 so as to be inclined with respect to the optical axis 23 of the object reflected light in the direction orthogonal to the irradiated surface of the document 9 .

Further, the optical axis of the irradiation light 21, 22 of one of the two light source substrates 10, 10 is symmetric with respect to the optical axis 23 of the object reflected light in a direction orthogonal to the irradiated surface of the document 9. The two light source substrates 10 and 10 are arranged so as to be substantially symmetric with respect to the optical axes of the irradiation lights 21 and 22 of the other light source substrate 10 as axes.

  Further, the reflected light from the object passes through the slit 4 a provided between the two light source substrates 10 and 10, enters the reflection mirror 4 b, is reflected, and is output to the outside of the illumination unit 4. .

  The illumination unit 4 uses the two light source substrates 10 and 10 as described above. However, as shown in FIG. The illumination unit 4 using the two light source substrates 10 can enhance the irradiation light as compared with the illumination unit composed of one light source substrate 10.

  Next, the image reading apparatus in the present embodiment will be described. The image reading apparatus in the present embodiment is configured to include the illumination unit 4 described above. FIG. 9 is a cross-sectional view of the image reading apparatus 1 in the present embodiment.

  In FIG. 9, the front side is the upper side of the image reading device 1, the back side is the lower side of the image reading device 1, the left direction is the front of the image reading device 1, and the right direction is the image reading. It is behind the device 1.

  In FIG. 9, the image reading apparatus 1 according to the present embodiment includes a document placing plate 2, a document pressing plate 3, the illumination unit 4, and a photoelectric conversion unit 5. In FIG. 9, only the light source substrate 10, the slit 4 a, and the reflection mirror 4 b that are constituent elements of the illumination unit 4 are illustrated as the illumination unit 4 for easy understanding.

  In the image reading apparatus 1 described above, the document placing plate 2 has a plate shape in which the front-rear direction is a rectangle whose longitudinal direction is the longitudinal direction, and is formed of a translucent material such as glass. The document placing plate 2 has a function of placing the document 9 on the surface of the document placing plate 2. The document placing plate 2 is formed so that the width of the document placing plate 2 is wider than the maximum width of the document placed on the surface of the document placing plate 2.

  The document placing plate 2 is mounted on a pedestal 6. Inside the pedestal 6, an internal space 6 a is formed with the lower surface of the document placing plate 2 as a ceiling, and the illumination unit 4 and the photoelectric conversion unit 5 are installed in the internal space 6 a.

  As shown in FIG. 9, the photoelectric conversion unit 5 includes two reflecting mirrors 5a, a lens group 5b, and an image sensor 5c formed of a CCD. Among these, the two reflecting mirrors 5 a are held by holding pieces provided in an illumination unit holding drive unit (not shown) of the illumination unit 4, and move integrally with the illumination unit 4.

  The first reflection mirror 5a is disposed in front of the illumination unit 4 and reflects light output from the illumination unit 4 downward. The second reflecting mirror 5a is disposed below the first reflecting mirror 5a, and reflects the light reflected by the first reflecting mirror 5a backward. Then, the light reflected by the second reflecting mirror 5a passes through the lens group 5b, is converged on the image pickup device 5c made of CCD, and is converted into an image signal. The document 9 is read by the conversion to the image signal.

  The document pressing plate 3 is installed on the document placing plate 2. The document pressing plate 3 includes a rotation support shaft 3 b at the front end of the document pressing plate 3. The rotation support shaft 3b is held by a rotation support shaft holding piece (not shown) attached to the pedestal 6, and is attached to the document placing plate 2 attached to the pedestal 6 with the rotation support shaft 3b as a rotation center. On the other hand, the document pressing plate 3 is attached to the base 6 so as to be rotatable.

  Therefore, the document pressing plate 3 can be opened and closed with respect to the document placing plate 2 by the rotation support shaft 3b. With this opening / closing function, when the image reading apparatus 1 is used, first, the document pressing plate 3 is opened with respect to the document placing plate 2, the document 9 is placed on the surface of the document placing plate 2, and then the document pressing plate 2 is pressed. Close the plate 3.

  Then, when the original 9 is pressed by the original pressing plate 3 so that the original 9 does not move, a reading instruction button (not shown) is pressed to read the original 9 as described above. When the reading is completed, the document pressing plate 3 is opened again and the document 9 is taken out.

  The document pressing plate 3 has a reflective surface 3 a formed on the lower surface of the document pressing plate 3. The reflecting surface 3a is made of a material having a high light reflectance. As this material, a planar metal plate made of stainless steel (SUS), a planar high reflectivity film, or the like is used.

  If the reflecting surface 3a of the document pressing plate 3 is made of stainless steel (SUS), the stainless steel is not easily rusted, so that the gloss can be maintained and the high reflectance can be maintained. Further, when the reflecting surface 3a is formed of a planar high reflectivity film, the high reflectivity can be maintained.

  As described above, the image reading apparatus 1 uses the illumination unit 4, and the illumination unit 4 uses the light source substrate 10. As described above, the light source substrate 10 has a feature that can suppress uneven brightness of light emitted from the light source substrate 10. Then, in order to see this effect, the experiment conducted using said image reading apparatus 1 and its result are demonstrated below.

  In the above experiment, in order to compare the effects, the light source substrate 10A shown in FIG. 10 and the light source substrate 10B shown in FIG. Then, the light source substrate 10A, the light source substrate 10B, and the light source substrate 10 are respectively attached to the illumination unit 4 of the image reading apparatus 1, and the document surface is not described with the surface color of the document. Were read by a CCD which is the image pickup device 5c of the image reading apparatus 1 and compared.

Light source substrates 10A, in the light source substrate 10, without providing the black layer 13a, the surface of the substrate 12 is obtained by a state of exposing the white color layer 12d. The light source substrate 10B is formed by replacing the black layer 13 with a black layer 13a in which the width of the black layer 13 in the light source substrate 10 is 3 mm instead of 1 mm.

  12 to 14 are graphs showing the results of the above-described experiment, in which the vertical axis represents the density level, that is, the output level of the CCD that is the image pickup device 5c of the image reading apparatus 1, and the horizontal axis represents the image reading apparatus. The distance in the width direction of one mounting plate 2 is shown in the order of the dots of the reading resolution. In the above graph, the illuminance is displayed for each of R (red), G (green), and B (blue), which are the three elements of light. 12 to 14, FIG. 12 shows the light source substrate 10 </ b> A, FIG. 13 shows the light source substrate 10 </ b> B, and FIG. 14 shows the light source substrate 10.

  12 to 14, the waveform of the light source substrate 10 shown in FIG. 14 is gentle compared to the case of the light source substrate 10 </ b> A shown in FIG. 12 or the light source substrate 10 </ b> B shown in FIG. 13. This indicates that the light / dark unevenness of the light emitted from the light source substrate 10 is less than the light / dark unevenness of the light irradiated from the light source substrate 10A or the light source substrate 10B.

  Next, a theoretical analysis of the above results was attempted. 15 to 17 show the light intensity DL of the direct light emitted from the light source diode 10 in the light source substrate 10A, the light source substrate 10B, and the light source substrate 10 and the light intensity RL of the substrate reflected light. Is an illuminance analysis diagram showing the distance from the light emitting diode 11 as a light source. In each figure, the document reading position 9a indicates the position of the placement plate of the image reading apparatus 1 on which the surface of the document to be read is placed.

  FIG. 18 is a graph showing the illuminance at the original reading position 9a in FIGS. 15 to 17, where the vertical axis represents the illuminance and the horizontal axis represents the distance in the direction in which the light emitting diodes 11 are arranged. Moreover, P1, P2, and P3 have shown the point of the same name in FIGS.

  In the case of the light source substrate 10A in FIG. 15 described above, the substrate reflected light is not suppressed because the black layer 13a is not provided. Therefore, the illuminance at the document reading position 9a in this case is a curve shown as the light source substrate 10A in FIG.

  On the other hand, in the case of the light source substrate 10B in FIG. 16, since the black layer 13a having a width of 3 mm is provided, the substrate reflected light is suppressed. Accordingly, the illuminance at the document reading position 9a in this case is a curve shown as the light source substrate 10B in FIG. 18, and the illuminance is reduced by the amount of substrate reflected light being suppressed. That is, in this case, as compared with the case of the light source substrate 10A, only the illuminance is lowered, and unevenness of light cannot be suppressed.

  In the case of the light source substrate 10A or the light source substrate 10B, in the case of the light source substrate 10 in FIG. 17, the black layer 13 corresponding to the light reflection suppression area is The light emitting surface 11a is formed with a width of 1 mm which is narrower than the width of 2 mm.

  Therefore, the light emitted from the central portion of the light emitting surface 11 a of the light emitting diode 11 is suppressed from being reflected by the black layer 13, and the irradiation light is mainly the direct light emitted from the light emitting diode 11.

  On the other hand, the light emitted from the peripheral portions of both ends of the light emitting surface 11a of the light emitting diode 11 has a black layer 13 because the black layer 13 which is a light reflection suppression area is narrower than the width of the light emitting surface 11a of the light emitting diode 11. Since reflection is performed at portions other than 13, the reflection is not suppressed, and the irradiation light is composed of direct light and substrate reflected light.

  Therefore, the illuminance at the document reading position 9a in this case is a curve shown as the light source substrate 10 in FIG. 18, and the curve is gentle compared to the case of the light source substrate 10A or the light source substrate 10B. In other words, light unevenness of light is suppressed as the entire irradiation light on the light source substrate 10.

  Next, the following experiment was performed following the above-described experiment on the uneven brightness of light. That is, as described above, in the image reading apparatus 1 described above, the white layer 12d of the light source substrate 10 used in the illumination unit 4 provided in the image reading apparatus 1 is as shown in FIGS. Further, it is formed on the white resist layer 12c. This is because by making the resist layer 12c white, the reflectance of light can be made higher than when the resist layer 12c has a color other than white.

  The experiment described below was conducted to confirm this effect. In this experiment, the above-described light source substrate 10 and the light source substrate 10 are the same as the light source substrate 10 except that the color of the resist layer 12c is not white but green, which is a conventional color. 10C was created.

  That is, in the light source substrate 10, the white layer 12d is formed on the white resist layer 12c, whereas in the light source substrate 10C, the white layer 12d is formed on the green resist layer 12c.

  In this experiment, the light source substrate 10 and the light source substrate 10C are respectively attached to the illumination unit 4 of the image reading apparatus 1, and the portions of the document placement plate 2 of the image reading apparatus 1 that are directly above the illumination unit 4 are touched. The illuminance was measured with a luminometer.

FIG. 19 shows the results of this experiment. As can be seen from FIG. 19, the light source substrate 10 has higher illuminance than the light source substrate 10C. Therefore, it can be seen that the reflectance of light can be increased by setting the resist layer 12c of the light source substrate 10 to be white, as compared with the case where the resist layer 12c has a color other than white.
According to the light source substrate 10 in the present embodiment described above, the black layer 13 that is the light reflection suppression area of the light source substrate 10 is formed with a width narrower than the width of the light emitting surface 11 a of the light emitting diode 11. Therefore, reflection of light emitted from the central portion of the light emitting surface 11a of the light emitting diode 11 is suppressed by the black layer 13 which is a light reflection suppressing area. Therefore, the light emitted from the light source substrate 10 is mainly direct light emitted from the light emitting diode 11.

  On the other hand, the light radiated from the peripheral portions of both ends of the light emitting surface 11a of the light emitting diode 11 is suppressed in light reflection because the black layer 13 as the light reflection suppressing area is narrower than the width of the light emitting surface 11a of the light emitting diode 11. Reflection is not suppressed because it is reflected at portions other than the area. Therefore, the irradiation light of the light source substrate 10 is composed of direct light radiated from the light emitting diode 11 and substrate reflected light.

  Therefore, the brightness unevenness of light is suppressed as the whole irradiation light of the light source substrate 10. In addition, the light source substrate 10 is configured by arranging the light emitting diodes 11 on the substrate at intervals, and the structure is simple. Therefore, the structure of the light source substrate 10 can be simplified, and unevenness of the light of the light source substrate 10 can be suppressed.

  Moreover, the black layer 13 which is the light reflection suppression area of the light source board | substrate 10 is planar, and the color of this surface is black. Therefore, the light reflectance of the light reflection suppression area of the light source substrate 10 can be lowered compared to other colors.

Further, between the light emitting surface 11a of the light emitting diode 11 on the surface of the light source substrate 10 and the end portion of the substrate 12, light reflection acceleration having a light reflectance higher than that of the light reflection suppression area is provided in portions other than the light reflection suppression area. An area is formed.

  Therefore, reflection of the light emitted from the peripheral portions at both ends of the light emitting surface 11a of the light emitting diode 11 is promoted. Accordingly, it is possible to enhance the irradiation light composed of the direct light and the substrate reflected light from the peripheral portions of the light emitting surface 11a.

  Therefore, the brightness of the irradiation light by the radiated light from both ends of the light emitting surface 11a can be brought close to the brightness of the direct light-based irradiation light from the central portion of the light emitting surface 11a of the light emitting diode 11, Light unevenness of the light from the light source substrate 10 can be suppressed.

  Further, the light reflection promoting area of the light source substrate 10 is planar, and the color of this surface is white. Therefore, the light reflectance of the light reflection promotion area of the light source substrate 10 can be increased compared to other colors.

  Furthermore, a white light reflection promoting area can be formed on the surface of the white resist layer 12 c formed on the surface of the substrate 12. Therefore, by making the resist layer 12c white, the reflectance of light in the white light reflection promoting area formed thereon can be further increased.

  Moreover, the illumination unit 4 in this Embodiment provided with the light source board | substrate 10 mentioned above is equipped with the effect | action and effect with which the light source board | substrate 10 mentioned above is provided. In addition, the image reading apparatus 1 according to the present embodiment including the above-described illumination unit 4 has the functions and effects included in the above-described illumination unit 4.

  Furthermore, the image reading apparatus 1 in the present embodiment described above can be used as a part of the image forming apparatus. That is, an image forming apparatus using the image reading apparatus 1 in the present embodiment described above can be configured. The image forming apparatus forms a recording image based on the image of the original read by the image reading apparatus and records it on a recording sheet. The image forming apparatus provided with this image reading apparatus has the operations and effects of the image reading apparatus 1 in the present embodiment described above.

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Original mounting plate 3 Original press board 3a Reflective surface 3b Rotating spindle 4 Illumination unit 4a Slit 4b Reflective mirror 5 Photoelectric conversion part 5a Reflective mirror 5b Lens group 5c Image pick-up element 6 Base 6a Internal space 9 Original 9a Original Reading position 10 Light source substrate 10A Light source substrate 10B Light source substrate 10C Light source substrate 11 Light emitting diode 11a Light emitting surface 12 Substrate 12a Base material 12b Copper foil pattern 12c Resist layer 12d White layer 13 Black layer 13a Black layer 21 Direct light 22 Substrate reflected light 23 Target Optical axis of object reflected light

Claims (10)

A plurality of light emitting elements each having a light emitting surface, arranged in a row at intervals on the surface of the substrate, and emitting light from the light emitting surface along the surface of the substrate,
A light reflection suppression area is formed on the surface of the substrate,
The light reflection suppression area is provided from the light emitting surface to the end of the substrate along a direction orthogonal to the light emitting surface, and has a width narrower than the width of the light emitting surface,
On the surface of the substrate, a portion other than the portion where the light reflection suppression area is formed between the light emitting surface and the end of the substrate has a light reflection promotion area having a light reflectance higher than that of the light reflection suppression area. It is comprised by these, The light source device characterized by the above-mentioned. The light source device according to claim 1,
The light-emitting device is a light source device that is a side-type light-emitting element having the light-emitting surface on a side surface. The light source device according to claim 1 or 2,
The light reflection suppressing area is a light source device that is a black or gray surface. In the light source device according to any one of claims 1 to 3,
The light reflection promoting area is a light source device that is a white surface. The light source device according to claim 4,
The white light reflection promoting area is a light source device formed by silk printing. The light source device according to claim 4 or 5,
The white light reflection promotion area is a light source device formed on the surface of a white resist layer formed on the surface of the substrate. A light irradiation apparatus comprising the light source device according to claim 1, wherein the light irradiation device irradiates light to the light irradiation object and obtains reflected light from the light irradiation object. Because
In the light source device, the light irradiation in a direction in which an optical axis of irradiation light for irradiating the light irradiation target with light emitted from the light emitting surface of the light source device is orthogonal to the surface to be irradiated of the light irradiation target. A light irradiation device disposed at a position inclined with respect to an optical axis of reflected light from an object. In the light irradiation apparatus of Claim 7,
Two light source devices are provided, and the light source device is a reflection from the light irradiation object in a direction in which the optical axis of the irradiation light of one of the light source devices is orthogonal to the irradiated surface of the light irradiation object. A light irradiation device disposed at a position symmetrical to the optical axis of irradiation light of the other light source device with the optical axis of light as the axis of symmetry. The light irradiation apparatus according to claim 7 or 8, wherein the light irradiation object is irradiated with light, and the reflected light from the light irradiation object is output.
An image reading device comprising: an image sensor that converts light output from the light irradiation device into an image signal.   An image forming apparatus comprising the image reading apparatus according to claim 9, wherein the image forming apparatus forms an image based on an image read by the image reading apparatus.

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